1. Field of the Invention
The present invention is directed to the field of photography and, more specifically, to improvements in cameras having a built-in electronic flash unit and manually operable first and second actuators for sequentially charging the flash unit's storage capacitor and then initiating an automatic cycle of camera operation.
2. Description of the Prior Art
The present invention is directed to improvements in a camera of the type disclosed in a commonly-assigned copending application, Ser. No. 054,598 entitled "Camera With Folding Flash Unit" filed by Bruce K. Johnson and George D. Whiteside on July 3, 1979. This camera includes a built-in electronic or strobe-type flash unit that is movable relative to the camera housing between an erect operative position and a folded storage position. The camera is preferably of the self-developing type which utilizes a film pack having a flat battery therein for powering the flash unit and the camera's electrical system. In order to prevent exceeding the battery's power delivery rate and to minimize power drain, it is preferable to provide a sequential actuating system wherein the flash unit's storage capacitor is charged to full capacity immediately preceding the film exposure and processing phase.
To provide this sequential actuating system, the camera disclosed in the above-noted copending application includes an elongated actuator housing, on one side of the camera, having a rearwardly facing first actuator or push button at the trailing end and a forwardly facing second actuator or push button at the leading end. In use, the first actuator is pushed forwardly to cause an internal electrical switch to be closed thereby connecting the battery in the film pack to the flash unit for capacitor charging. When the capacitor is fully charged, as indicated by a visual signal in the viewfinder, the user then pushes rearwardly on the second actuator to mechanically move a slider member located totally within the camera housing, which is effective to close an internal electrical switch that initiates an automatic cycle of camera operation including film exposure with supplemental illumination provided by the flash unit.
While this system works well, it does have several limitations. First, it is somewhat awkward for the user not to push rearwardly on the forward cycle actuator button with his second finger during the time period when he is pushing forwardly with his thumb on the rearwardly facing flash charge actuator. Secondly, in anticipation of the user inadvertently operating the actuators in the wrong sequence, it may be necessary to provide an additional logic circuit to electrically block out a camera start signal produced by operation of the forward actuator until the flash unit capacitor is fully charged. Once this lock-out logic is built into the system, the user is denied the option of initiating an automatic cycle of camera operation that does not include the firing of the flash unit when scene lighting conditions so warrant. Also, no provision is made for inhibiting operation of the flash charge actuator when the camera is not in use which could possibly cause excessive battery drain if the camera is stored under certain conditions, such as in a packed suitcase, where the flash charge actuator is inadvertently and unknowingly pushed forward.
Therefore, it is an object of the present invention to provide such a camera having an improved dual actuator system that eliminates the awkwardness and confusion of the forward and aft placement of the first and second actuators.
It is another object of the invention to provide a dual actuator system that has provisions for allowing the user the option of bypassing the flash charge phase and directly initiating an automatic cycle of camera operation that does not include firing the flash unit.
The internal slider member, responsive to operation of the second actuator for closing a normally open cycle start switch, has proven to be an extremely reliable device in the Pronto! and OneStep cameras manufactured by Polaroid Corporation, Cambridge, Massachusetts.
Therefore, it is yet another object of the present invention to provide an improved dual actuator system that retains such a slider.
Another object of the invention is to provide an improved dual actuator system which includes provisions for latching at least one of the actuators, preferably the flash charge actuator, to prevent inadvertent operation of the actuator when the flash unit is located in its folded storage position.
The slider device mentioned above and its associated switching system is of the type set forth in detail in commonly-assigned U.S. Pat. No. 4,040,072.
For representative examples of other self-developing cameras having dual actuators for flash charge and exposure initiation, reference may be had to commonly-assigned U.S. Pat. Nos. 4,001,640 and 4,085,414. It will be noted, however, that the placement of these dual actuators makes them somewhat awkward to use and the structure therein is not compatible with retaining the slider member.
The concept of latching or covering one or more camera actuators to prevent inadvertent operation of the camera when not in use is, of course, well known in the prior art. For example, commonly-assigned U.S. Pat. No. 3,550,513 shows a shutter actuator button that is movable between operative and latched positions. U.S. Pat. No. 2,783,696 shows, in FIG. 11, a camera wherein the actuating button is covered by an extension cover section on a folding flash unit. U.S. Pat. No. 3,427,943 discloses a camera in which a lens cover located in its closed position releasably latches a camera actuator. Also, U.S. Pat. No. 2,011,895 shows a detent on an erecting link that latches the camera actuator when the lens board is folded. Further, U.S. Pat. No. Re 27,362 discloses a camera having an actuator in a handle that is movable to a folded position wherein the actuator is inaccessible. For an example of a camera having a telescoping body that covers and denies access to the actuator button when the body is in its retracted position, see commonly-assigned U.S. Pat. No. 4,132,471.